Linux Security Fundamentals

Introduction

Linux security is critical for protecting sensitive data and maintaining the integrity of the system. This lesson covers fundamental concepts that every Linux administrator should know.

Key Concepts

• Authentication: Verifying user identity.
• Authorization: Granting users permission to access resources.
• Accounting: Tracking user actions.
• Encryption: Protecting data confidentiality.

User Management

Manage users and groups effectively to enhance security:

sudo adduser username
            

sudo deluser username
            

File Permissions

File permissions control access to files and directories. Use the chmod command to modify permissions:

chmod 755 filename
        

In this example, the owner has read, write, and execute permissions, while the group and others have read and execute permissions.

Network Security

Securing network services is crucial:

• Use SSH for secure remote access.
• Disable unused services and ports.
• Implement network segmentation.

Firewall Configuration

Use iptables or ufw for firewall management:

sudo ufw enable
sudo ufw allow ssh
sudo ufw deny 23
        

Best Practices

Follow these best practices for Linux security:

• Regularly update the system.
• Use strong passwords and authentication methods.
• Conduct regular security audits.
• Backup critical data regularly.

FAQ